1. Field of the Invention
This invention relates to a transparent electromagnetic radiation shield material and a transparent electromagnetic radiation shield panel for placement in front of a display device or other such source of electromagnetic radiation to shield the viewer from electromagnetic radiation, and to methods of producing the material and panel. It particularly relates to a panel suitable for a large plasma display.
2. Description of the Background Art
An electromagnetic radiation shield material for placement in front of a display device or other source of electromagnetic radiation is required to have not only excellent electromagnetic radiation shielding capability but also excellent transparency (optical transmittance), good clarity (degree of coating blackness etc.), wide viewing angle and the like. Japanese Patent Application Laid-Open No. 9-298384 teaches an electromagnetic radiation shield material meeting these requirements to some extent. Specifically, this laid-open patent application teaches a method wherein "a step of providing a black dyed layer on a transparent base material, a step of providing a metallic layer on the black dyed layer, a step of providing a patterned resist layer on the metallic layer and a step of removing portions of the metallic layer not covered by the resist layer by etching with an etching solution are conducted in succession, portions of the black dyed layer not covered by the patterned metallic layer being decolored in the etching step."
Generally, however, a sufficient degree of coating blackness and good clarity are hard to obtain when a black dye is used in a black resin layer. The dye content and/or the resin layer thickness therefore has to be increased.
Moreover, when the etching solution for the metallic layer is used to decolor and extract the black dye, the metallic layer comes to be over-etched owing to the long time needed for the decoloration.